Recently, in oil-related industry applications, there have been demands for steel materials which have excellent strength, in addition to being corrosion resistant. As a steel material having high strength, a high nitrogen duplex stainless steel disclosed in JP5-132741A (Patent Literature 1), and a martensitic stainless steel containing 12 to 13 mass % of Cr disclosed in WO2008/026594 (Patent Literature 2) have been put into use.
When producing a welded joint which uses such a high strength stainless steel as the base material, high strength is also required for the weld metal. Further, high toughness is also required for the weld metal.
Meanwhile, among various welding methods, gas shielded arc welding provides good welding properties. Accordingly, the gas shielded arc welding has been utilized for the welding of various steel materials. The gas shielded arc welding includes a GTA (Gas Tungsten Arc) welding method and a GMA (Gas Metal Arc) welding method. The GTA welding method, which is also called a non-consumable type gas shielded arc welding, principally melts the base material with tungsten as the electrode to achieve joining. The GMA welding method, which is also called a consumable electrode type gas shielded arc welding, uses a welding consumable as the electrode.
Generally, the GTA welding method is applied for the welding of stainless steel. This is because the GTA welding method facilitates forming high quality weld metal. JP2001-3589A (Patent Literature 3) and JP8-260101 (Patent Literature 4) propose GTA welding which uses a high-nitrogen similar-metal welding material to obtain weld metal having high strength and high toughness.